From my study of ember dragons, they have many strengths, and many weaknesses. During all of their life they are protected by heat and/or a hard thin shell. As an egg, this dragon has heat emitting from the embryo, which goes straight through the shell. They lose this ability as they grow. This heat protects them from dragons that strayed from their biome, but all volcano dragons can get past the heat easily, but only truly crazy dragons would hurt an ember dragon's egg, therefore invoking a whole clan of ember dragons' wrath. The only reason humans can touch the egg is because even as an egg, the embryo is very smart, no matter what stage it's in. The embryo senses a human, and since the dragons have been affiliated with humans for centuries, the ember dragons feel like all humans are part of every dragon's clan. So, then they lower the heat emitting from them, allowing the human to come towards them. This is also why ember dragons are not hot to the touch. When the eggs hatch, the hatchlings lose the hard thin shell, though their heat grows so strong that only their own breed, hellfire dragons, and humans can get close to them without turning to ashes. This is why ember dragons usually pick hellfire dragons to nurse for them if they cannot supply the milk they need to feed the hatchling, and there's not another girl ember dragon in the clan. When the hatchling matures, it grows the hard thin shell on the back, protecting its spine, while the stomach still has the heat from before it matured, not allowing most dragons to harm it's most vital organs. By this time, like most dragons, they have teeth and now eat meat regularly. When ember dragons are fully grown, they lose most of the heat they had, as the hard thin shell stops most of the heat from getting through, and time has cooled it down. Now the cracks where heat used to come from is their only weakness. If a dragon gets its claws in the cracks, then pulls off part of the shell, the ember dragon is completely vulnerable. So what used to be their greatest strength became their greatest weakness. That's sad.
Now, time for the mating ritual. This includes the ember dragon's skin under the hard thin shell heating up immensely, which is much hotter than when it was a hatchling, which starts the process of molting. When all of the shell is off, they go find any dragon they think would be a good mate, and battle each other while also seeing if they can stand each other's heat. Most coast dragons can't stand that much heat, which is why eggs with ember and coast dragon parents are so rare. Fully grown ember dragons without their shell can scar a human for life, so all ember dragons, feeling loyal to the humans, get together the night before their mating season starts, renew a truce with daydream dragons by simply sleeping next to each other. But while the daydream dragons sleep, for a brief period of time the ember dragons whisper into their ears about ember dragons having their shells, which puts that idea into the daydream dragons' subconcious part of their minds for all of the ember dragons' mating season, which also uses the accidental power of the daydream dragons to make humans see ember dragons with their shells year-round.
During Christmas time in 2011, there was an increased power of Christmas, which caused ember dragons to turn colors, and at one point, have Christmas lights appear on them. Nobody knows where the source of the Christmas spirit came from, but my theory is it was from the combined magic of the magi dragons and the complete spirit of Christmas in one breed of dragon. The winter magi dragons. They had an immense effect on most dragons. They were probably using their powerful Christmas magic to give every dragon some Christmas fun.